Three countries Environmental Ministers agreed on launching the joint　research on cities towards decarbonization and sustainable development　in Joint Communiqué at The 20th Tripartite Environment Ministers　Meeting among China, Japan and Korea in June 2018, Suzhou, China. We organized the first joint research workshop at Beijing in Oct 2018 with researchers, national governmental officials, local governmental officials and others to discuss about best practices from each 3 cities from 3 countries and national policies. This side event seeks to chart the zero carbon way by introducing best practices in China, Japan and Korea.